Question

How are arteries and veins connected?

Answer 1

There are three types of blood vessels present in our body, these are arteries, veins, and capillaries. Each of these is very essential for the circulation of blood.

Complete answer:
The arteries carry oxygenated blood from the heart to all the parts of the body, whereas veins carry the blood back to the heart. Arteries are tough from the outside, but from inside they contain a smooth line of epithelial cells that help in the easy flow of the blood. They also contain a middle layer which is very strong and muscular that helps in pumping the blood throughout the body. The Aorta carries the blood from the heart to the body and the pulmonary artery carries blood from the heart to the lungs.
The veins are very similar to the arteries but not as thick and strong as them. Veins have a special feature of the presence of valves that prevents the backflow of the blood. Veins are required to ensure the flow of blood against gravity as well, thus valves play an important role. Arteries do not require valves as the pressure from the heart is enough for the blood to flow in one direction. The Vena cava carries deoxygenated blood from the body to the heart and the pulmonary vein carries oxygenated blood from the lungs to the heart.
The arteries and veins are connected through the capillaries. The actual exchange between oxygen and carbon dioxide occurs when the arteries deliver oxygenated blood to the capillaries. The capillaries then exchange the deoxygenated blood with the veins which transport it back to the lungs and heart.

Note: Although blood vessels are very tiny, they cover our whole body. The smallest blood vessel is of only 5 micrometers. Capillaries are responsible for occurrence of material exchange between the tissue cells and blood.